Astonishingly, neither of the two Whitefriars reference books contains a list of design registrations, patents, and registered trade marks. It's where you start with research, and the two museum-trained authors should have known this and done it. Timberlake, Reynolds, Gulliver, Cottle, Stewart & Stewart, Bowey & Parsons, and even Williams-Thomas, none of them museum professionals, all did it, properly.
So far I've found eight Whitefriars design registrations in the period 1890 to 1945, none of which I've ever seen marked on their glass. 543290 is not a Whitefriars registration, but that of a London designer. The vase was certainly made by Whitefriars â€” Jackson lists it as pattern 916 â€” and they made it in two sizes, but it could have been made by others, so, to be certain of a Whitefriars attribution, you should check the registration on the base with a known Whitefriars example for a match on the lettering.
The standard reference on this design registration is Gulliver, p.86. There is no need to plagiarise Mervyn Gulliver's work here as anyone seriously interested in British glass will own or have access to a copy of this important publication. If not, please buy one or borrow it from your library.
Note that I don't comment on live ebay listings. My comments here are on a registered design.